The sweeping plan, which includes a 13-year path to citizenship and guest worker programs, takes advantage of the changed political alignment of the U.S.

WASHINGTON — After months of negotiations, a bipartisan group of eight senators is poised to offer a sweeping bill to rewrite the nation's immigration laws this week, taking advantage of a changed political alignment that, for the first time in nearly a generation, appears to have opened the way for comprehensive legislation.

The bill would chart a 13-year path to citizenship for most of the 11 million people in this country without proper legal status, spend billions of dollars more on border security, create new legal guest worker programs for low-income jobs and farm labor, require new verification measures for most companies hiring new workers and significantly expand overall immigration to the U.S. for the next decade, according to an outline obtained by The Times' Washington bureau.

The legalization program would amount to the largest such effort any nation has attempted, affecting more than three times as many people as the Reagan-era immigration reform law. But it is only one part of the legislation, and perhaps not the portion with the greatest impact.

The agricultural workforce — where half the workers currently have no legal status — would be transformed by a new guest worker program that is designed to bring more than 300,000 immigrant farmworkers to the nation's fields over the next decade and provide field workers an expedited pathway to citizenship. A new visa program for housecleaners, landscapers and other low-skill occupations would be created, while high-tech industries would be allowed to double the number of foreign workers they use.

All told, the country's current inflow of about 1 million legal immigrants a year could grow by half over the next decade.

The bill also would probably spur a spending spree on the Southwest border as the government rolls out more surveillance technology, including unmanned drones and military-grade radar, to detect people crossing into the United States.

Although Congress has deadlocked repeatedly on immigration policy, leading figures in both parties expect that the legislation, expected to run hundreds of pages, stands an excellent chance of approval in the Senate, which plans to begin debate on it next month, and that some version of it could become law by year's end.

That would make the effort the first comprehensive immigration overhaul since the 1986 amnesty law signed by then-President Reagan.

"I think we are on the cusp of history here. This is a really big deal," said Marshall Fitz, an immigration expert at the Center for American Progress, a liberal think tank in Washington. "We are operating in a Washington environment that is so dysfunctional, so political, so partisan and yet on this issue.... eight members came together on this from a full ideological spectrum — that is historic."

Opponents warn that American workers will see their wages erode in the face of greater competition from migrants. Supporters counter that the bill would benefit the U.S. economy by bringing the current unauthorized population out of legal limbo and by providing a steady flow of legal workers for industries with labor shortages.

The legislative work in Washington reflects the changed dynamic in the country, as polls show a majority of Americans back some type of legal status for those living here without proper authorization.

Rather than viewing immigrants as a threat or burden to society, increasing numbers of Americans hold positive views of the contributions immigrants make, polls show.

That shift, along with the growing power of Latino voters, many of whom have made immigration reform a priority, appears to have broken a deadlock on the issue. After the overwhelming Latino vote for President Obama in 2012, many Republican strategists decided their party had little choice but to embrace reform. They tapped Sen. Marco Rubio, the rising tea party Republican from Florida, as their front man in talks with Democratic leaders and the handful of Republicans who had previously supported a legalization plan.

"What we have seen is, I think, a remarkable — in Washington — level of consensus between and support for bipartisan and comprehensive immigration reform," said White House spokesman Jay Carney on Monday.

For months, the eight senators — four Democrats and four Republicans — have been meeting privately, often in the office of Sen. Charles E. Schumer (D-N.Y.) steps from the Senate floor, as the contours of the bill took shape.